Mastitis, an infectious disease of the udder, is the most costly disease in U.S. animal agriculture. The condition is widespread among dairy cattle and exacts a high toll in lowered milk yield and reduced milk quality due to changes in the composition of the milk. Mastitis and mastitis control are complex problems, but good premilking udder hygiene has been recognized as a basic factor in the reduction and prevention of mastitis. Milking machines, the use of separate milking parlors, and pipeline milking have improved the sanitary conditions under which milk is handled on the farm. The milking parlor is generally used when the cows are not housed in a stanchion barn, but are allowed to run loose. The cows are brought into the parlor, and their flanks, udders and teats are washed and dried before attaching the milking machines. The double chamber teat cup provides the interface between the cow and the milking machine. The double chamber teat cup with a pulsating outer chamber is employed in practically all milking machines in use today. The unit is constituted of four teat cup shells, liners and a clawpiece (manifold). A partial vacuum supplied by a pulsator provides an intermittent opening and closing of the liner. When, during the milking phase, vacuum is applied to both the inner and outer chambers, the liner is open, and milk is withdrawn from the teat. When, during the resting phase, air is admitted to the outer chamber only, the liner closes upon the teat, and the flow of milk is interrupted. The milking machine has been recognized along with the milker's hands and udder washing materials as part of the environment which can affect the incidence, prevalence and severity of mastitis.
Dairymen use many methods of cleaning cow's udders and teats prior to milking, most of which involve washing away manure, mud and other environmental dirt contaminants with water. Commonly, the udder and teats are washed via use of a spray nozzle and each teat then individually massaged and dried with paper towels. Water is inevitably trapped by hair on the udders and flanks and drains downwardly during milking. The water collects on top of the inflation of the teat cup that surrounds a teat and is pulled by vacuum into the space between the inflation and the teat by the milking action. Subsequently, it ends up in the milk. Moreover, an abrupt reduction in vacuum can cause movement of air toward the teat end, and contaminated droplets may impact the teat end. The impact may also force bacteria in the teat duct into the teat cistern. Thus, the abrupt loss of vacuum caused by liner slips, machine drop-off or take-off without prior vacuum shut off are the types of positive variations which can force the contaminated water into the teat, an effect which can cause mastitis.
No matter how well the cow has been washed, water from the draining surface of the udder and flanks is contaminated with bacteria, the contaminated water collecting on the top of the inflation to be pulled by vacuum into the space between the inflation and the teat by the milking action, and sharp reductions in vacuum, these conditions causing the contaminated water to find its way into the milk to reduce milk quality and into the teats to increase the incidence of mastitis. Many farmers and researchers have experimented with premilking sanitizing teat dips and wash solutions. Some improvement in the quality of the milk has been made, it is believed, by the use of a teat dip subsequent to water spraying and cleaning the udder and teats, followed by attachment of the milking machine. In most premilking udder hygiene practices, however, sanitizing washes and teat dips have produced little or no benefit. In conventional practice, water continues the cleaner of choice for premilking udder hygiene; and, teat dips are applied after the milking phase has been completed. In any event, much of the problem, it is now recognized, is due to the contamination caused by the excess water which drains from the cow's flank, teats and udder during milking. Thus, there exists a profound need for improved, premilking udder hygiene.